Introduced `OutgoingEmailPublisher` for RabbitMQ-based email
queueing with message persistence, scalability, and reliability.
Added dependency injection support via `AddMessagingServicePublisher`
extension method. Enhanced RabbitMQ topology setup with exchanges,
queues, and Dead Letter Queues (DLQ).
Updated `DigitalData.MessagingService.Publisher.csproj` and
`DigitalData.MessagingService.RabbitMQ.csproj` to support
`net462`, `net480`, and `net8.0`. Added project references
and conditional package references for compatibility.
Integrated logging with `Microsoft.Extensions.Logging` and
used `System.Text.Json` for serialization. Implemented lazy
initialization for RabbitMQ channels to improve performance.
A new project, `DigitalData.MessagingService.Publisher`, has been added to the solution. The solution file (`DigitalData.MessagingService.sln`) was updated to include the project declaration, build configurations, and nesting under the appropriate parent project.
The new project targets `.NET 8.0` and includes the following configurations:
- Implicit Usings enabled.
- Nullable reference types enabled.
- Latest C# language version specified.
